Download MendeleyBiochemical and Structural Characterization of (South)-Methanocarbathymidine that Specifically Inhibits Growth of Herpes Simplex Virus Type 1 Thymidine Kinase-Transduced Osteosarcoma Cells
Schelling, P., Claus, M.T., Johner, R., Marquez, V.E., Schulz, G.E., Scapozza, L.(2004) J Biol Chem 279: 32832
- PubMed: 15163659
- DOI: https://doi.org/10.1074/jbc.M313343200
- Primary Citation of Related Structures:
1OF1 - PubMed Abstract:
Two analogs of the natural nucleoside dT featuring a pseudosugar with fixed conformation in place of the deoxyribosyl residue (carbathymidine analogs) were biochemically and structurally characterized for their acceptance by both human cytosolic thymidine kinase isoenzyme 1 (hTK1) and herpes simplex virus type 1 thymidine kinase (HSV1 TK) and subsequently tested in cell proliferation assays. 3'-exo-Methanocarbathymidine ((South)-methanocarbathymidine (S)-MCT), which is a substrate for HSV1 TK, specifically inhibited growth of HSV1 TK-transduced human osteosarcoma cells with an IC(50) value in the range of 15 microM without significant toxicity toward both hTK1-negative (TK(-)) and non-transduced cells. 2'-exo-Methanocarbathymidine ((North)-methanocarbathymidine (N)-MCT), which is a weak substrate for hTK1 and a substantial one for HSV1 TK, induced a specific growth inhibition in HSV1 TK-transfected cells comparable to that of (S)-MCT and ganciclovir. A growth inhibition activity was also observed with (N)-MCT and ganciclovir in non-transduced cells in a cell line-dependent manner, whereas TK(-) cells were not affected. The presented 1.95-A crystal structure of the complex (S)-MCT.HSV1 TK explains both the more favorable binding affinity and catalytic turnover of (S)-MCT for HSV1 TK over the North analog. Additionally the plasticity of the active site of the enzyme is addressed by comparing the binding of (North)- and (South)-carbathymidine analogs. The presented study of these two potent candidate prodrugs for HSV1 TK gene-directed enzyme prodrug therapy suggests that (S)-MCT may be even safer to use than its North counterpart (N)-MCT.
Organizational Affiliation:
Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH), Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
